Power Supply "Sense" Pins

[Ambient]

Well I got this power supply from allelctronics. Great price, but no instructions. The problem is that is has a + and- Sense connection and pins for 5V@8A, 3.3V@4A, and 2.5V@2A. They do not have any info on the power supply on their website, and the supplies that do have documentation say to hook up the Sense pins to the load or else the PS will be ruined permanently. But those details I found on the site were for supplies with just one output voltage. So the question is: Which output are the sense pins for? They are located next to the 2 5V pins on the pin header.

Power Supply: Power-One SP637.

 

[ericgibbs]

hi ambient,

Have a look at the diagrams on this site.

**broken link removed**

On my dual bench power supply the '+' sense lead and the +12Vout are just joined together and the '-' sense lead and the -12Vout
are joined. There is 'common sense' lead which is joined to the psu common 0Vout.

Usually they are used to sense the voltage at the actual load, correcting for any voltage drop in the psu leads to the load.

The warning is 'dont connect the psu outputs to the load using the sense leads on their own', you MUST use the psu output leads.

 

[Ambient]

yea I did see that on the site, but the problem is which Vout is the sense for. If it was for the 5V and I hooked it up to the 3.3 or 2.5V it would boost the power on the 5V thinking that there was that much of a drop. I will just hook them to the 5V and GND and hope for the best if no one knows for sure.

 

[ericgibbs]

hi,
I am assuming that you have a pair of sense lines for each voltage output, is that right?

 

[Ambient]

nope just one pair, + and -. But there are 3 ouput voltages and GND. Just + Vouts, no negative. So I know the S- goes to Ground.

 

[ericgibbs]

hi,
See what you mean about minimal data on the PS637 datasheet.
Browsed their website, no luck.

Sent them an email requesting +/-sense connections, I won't hold my breath.

If I do get a useful response, will let you know.

 

[Leftyretro]

Well I got this power supply from allelctronics. Great price, but no instructions. The problem is that is has a + and- Sense connection and pins for 5V@8A, 3.3V@4A, and 2.5V@2A. They do not have any info on the power supply on their website, and the supplies that do have documentation say to hook up the Sense pins to the load or else the PS will be ruined permanently. But those details I found on the site were for supplies with just one output voltage. So the question is: Which output are the sense pins for? They are located next to the 2 5V pins on the pin header.

Power Supply: Power-One SP637.

I've worked on lots of PS that have remote sensing feature, but can't recall one that had multi-outputs. I would assume because the sense pin is located next to the +5 pins and because the +5 supply has the highest current capacity that the +sense pin should be jumpered to a +5 pin.

A remote sensing input feature give you a choice of where you want the power supply regulator to get it's voltage feedback information from. It you jumper it at the power supply terminals the regulator will cause the regulation voltage to be correct at the power supply terminals. If however you have a long wiring length to your load and have a certain amount of voltage drop after reaching the load you can wire the sensing pin to the voltage wired at the load end and the PS regulator will 'compensate' for this voltage drop. That will insure the the regulated voltage value is accurate at the load end rather then the power supply end. This feature is seldom used and in most cases it's just jumpered at the power supply.

Good luck

Lefty

 

[ericgibbs]

hi ambient,

Email feedback from my enquiry:

>> Please contact our retail store at 818-997-1806 Van Nuys, CA. They are not technicians but can provide more help.

Thank you
Margarita

Any use?

 

[Ambient]

Thanks for the help, I will give them a call. It is out of production but hopefully they have a long time employee there who remembers.

 

[gmontag451]

I realize it's been more than a year since this message was started, but I thought I'd add to it since I was trying to find the answer to this very question about this very power supply, and didn't really get a solid answer here. So I just bought one and fiddled with it! Here's my experience:

It's the Power One power supply SP-637 or PS-637 (depending on which part of the All Electronics website you are looking at.) I connected a windshield wiper motor (for a Halloween prop) to the +5V and GND pins, which are clearly labeled on the board, and plugged the PS into the wall outlet. The motor worked fine, and I did not use the sense pins.

I also tried disconnecting and re-connecting the motor without unplugging the PS, since my Halloween show will turn the motor on and off. A different switching PS I bought has a one second delay before providing power when this happens, but with the PS-637, there is no delay in the motor starting, so I assume no continuous resistance load is necessary to start up the PS.

Michael

PS. I haven't seen it mentioned before, and I had to research, so I thought I'd mention: the ACL and ACN pins refer to AC Live (narrow plug blade) and AC Neutral (wide plug blade.)

 

[eblc1388]

The motor worked fine, and I did not use the sense pins.

This is normal design behavior for a dis-connected "sense" pin.

Because of the likely hood of the user forget to connect the sense wire or the connection become detached or broken in normal operation, which will definitely result in the power supply thinking the load voltage has fallen and tried to compensate until it is reaching max. output voltage, nearly all power supply manufacturers have connected the sense pin internally to the supply output terminal via a resistor or diode. This has little effect on the output regulation if the sense wire is intact.

However, should the sense signal is "lost" for whatever reason, the output voltage is maintained so the load is not damaged via over-voltage.